Shooting at higher ISO settings comes with its own set of problems, and noise is one of them. You can work with the luminance amount and detail sliders as well as clarity. You might want to look at some plug-ins. I use the Nik Collection which has a noise reduction component. But I think in general we all become overly concerned with noise. If you need to use higher ISO settings then do what you can to reduce noise, but then don't become obsessed if the image isn't completely noise free.
I would only add that the default settings in LR are the
general combination of settings which can be used as a reasonable starting point
that you are looking for. But each image has it's own demands, each camera has it's own advantages and disadvantages, and you as the processor have your own opinion on what is an acceptable amount of noise reduction for your images. So, in the end, it's what you are comfortable with and what you find acceptable.
Here is a video you may find helpful.
Thanks, I just watched the video link.
Looks like its trial and error utilizing the sliders based on user preferences.